ISVTX
if (ichar & ISVTX) {
if (ip->i_char & ISVTX) {
ip->i_char |= ISVTX;
if ((dir->i_char & ISVTX) &&
(ip->i_char & ISVTX) &&
if ((VTOI(vp)->i_mode & (ISVTX | IEXEC | IFDIR)) == ISVTX)
if ((dp->i_mode & ISVTX) &&
if ((ip->i_mode & (ISVTX | IEXEC | IFDIR)) == ISVTX)